After graduating in 1864, he worked for several years in various institutions and his dream was to start his own company. In 1871, the steel mill was started by a businessman called August Ritter, but due to Ritter's irregular work, the business became heavy and creditors sealed the factory. He was helped by his wife, Bertha Benz. She invested the money she received from her parents for her dowry, paid Augustine Ritter, and bought part of his business, so that the business fell entirely into Carl Benz and Bertha Benz.
It was at this plant that Benz started researching petrol engines. In 1878, he built a reliable, efficient two-speed petrol engine, and in 1879 he received a patent. Instead, he invented and patented a carburetor that would deliver petrol fuel efficiently to the engine. He also won patents on all of these by creating a clutch system, a gear system, and a water-cooled radiator system.